Download #MVA Content with PowerShell

#source - http://gallery.technet.microsoft.com/scriptcenter/Remove-Invalid-Characters-39fa17b1
#changed slightly for MSVA script

Function Remove-InvalidFileNameChars {
    <#
    .SYNOPSIS
    This is a PowerShell function to remove invalid characters from strings to be used as file names.

    .DESCRIPTION
    The function takes a string parameter called Name and returns a string that has been stripped of invalid file name characters, i.e. *, :, \, /.  The Name parameter will also receive input from the pipeline.

    .PARAMETER Name
    Specifies the file name to strip of invalid characters.

    .INPUTS
    Parameter Name accepts System.String objects from the pipeline.

    .OUTPUTS
    System.String.  Outpus a string object

    .EXAMPLE
    Remove-InvalidFileNameChars -Name "<This/name\is*an:illegal?filename>"
    PS C:\>Thisnameisanillegalfilename

    .NOTES
    It would be easiest to copy the function from the script file and place it in your profile.  However, you may also dot-source the script to load the function into PowerShell:
    i.e. PS C:\>. .\Remove-InvalidFileNameChars.ps1
    #>

    [CmdletBinding()]

    param([Parameter(Mandatory=$true,
        Position=0,
        ValueFromPipeline=$true, 
        ValueFromPipelineByPropertyName=$true)]
        [String]$Name
    )

    $result = [RegEx]::Replace($Name, "[{0}]" -f ([RegEx]::Escape([String][System.IO.Path]::GetInvalidFileNameChars())), '')
    $result = $result.Replace("Microsoft-Virtual-Academy", "")
    while($result.Contains("--"))
    {
        $result = $result.Replace("--", "-")
    }

    return $result.Trim("-")
}

cls

Write-Output ""
Write-Output ""
Write-Output ""
Write-Output ""
Write-Output ""
Write-Output ""
Write-Output ""
Write-Output ""
Write-Output ""
Write-Output ""
Write-Output "Starting"

$certPages = $("mcsd-application-lifecycle-management","mcsd-windows-store-apps-certification","mcsd-web-apps-certification")
$baseSaveLocation = "Z:\Learning\Microsoft Virtual Academy"

$pathToRemoveInvalidFileNameCharsScript = "$baseSaveLocation\Remove-InvalidFileNameChars.ps1"

#------------Don't edit below here----------------#

. "$pathToRemoveInvalidFileNameCharsScript"    
foreach($certPage in $certPages)
{
    $certUrl="http://www.microsoft.com/learning/en-us/$certPage.aspx"
    Write-Output "Downloading Page: $certUrl"
    $pageHtml=invoke-webrequest -uri $certUrl
    $destination="$baseSaveLocation\$(Remove-InvalidFileNameChars $certPage.Replace(" ","-"))"

    if (!(Test-Path $destination)) {
        New-Item -ItemType directory -Path $destination
    }
    
    $filteredLinks = $pageHtml.Links | Where-Object { $_.href.ToLower().StartsWith("http://www.microsoftvirtualacademy.com/training-courses/") } 

    foreach($link in $filteredLinks)
    {        
        Write-Output "Downloading Page: $($link.href)"
        $trainingPageHtml=invoke-webrequest -uri $link.href        
        [string]$trainingTitle = $trainingPageHtml.AllElements | Where-Object { $_.tagName.ToLower().StartsWith("title") } | Select-Object -ExpandProperty innerText {$_}
        $trainingTitle = $trainingTitle.Trim()
        $trainingDestination="$destination\$($link.innerText)-$(Remove-InvalidFileNameChars $trainingTitle.Replace(" ","-"))"

        if (!(Test-Path $trainingDestination)) {
            New-Item -ItemType directory -Path $trainingDestination
        }

        $idEducationTypePattern = [regex]"parent='(?<idEducationType>[^']*)'"
        [int]$idEducationType = $idEducationTypePattern.Match($trainingPageHtml.Content).Groups["idEducationType"].Value
        $jsonPostDataPattern = [regex]'showNextPanelEducationTypes((?<idEducationTypeSelected>[^"]*),(?<idEducationLevelSelected>[^"]*),(?<isApproved>[^"]*),(?<numControl>[^"]*),this)'
        foreach($jsonPostData in $jsonPostDataPattern.Matches($trainingPageHtml.Content))
        {

            [int]$idEducationTypeSelected = $jsonPostData.Groups["idEducationTypeSelected"].Value.TrimStart("(")
            [int]$idEducationLevelSelected = $jsonPostData.Groups["idEducationLevelSelected"].Value
            [int]$numControl = $jsonPostData.Groups["numControl"].Value
            $isApproved = $jsonPostData.Groups["isApproved"].Value
            $jsonPostUri = "http://www.microsoftvirtualacademy.com/Studies/EducationDetails.aspx/ShowNextPanelEducationTypes"
            $jsonPostBody = @{
                    idEducationTypeSelected = "$idEducationTypeSelected";
                    idEducationLevelSelected = $idEducationLevelSelected;
                    isSubscribe = $true;
                    selectedIsEnabled = "true";
                    numControl = $numControl;
                    idEducationType = "$idEducationType";
                    isApproved = "$isApproved";
                    culture="en-US"
                 }| ConvertTo-Json 

            $jsonInvokeResult = Invoke-RestMethod -Method Post -Uri $jsonPostUri -ContentType "application/json" -Body $jsonPostBody 
        
            $ctIDPattern = [regex]'openEmbeddedVideo((?<Id>.+));'
            foreach($ctID in $ctIDPattern.Matches($jsonInvokeResult.d.HtmlResponseMaterials))
            {
                $Id = $ctID.Groups["Id"].Value.TrimStart("(").Split(',')[0]
                $uriForTrainingVideo = "http://www.microsoftvirtualacademy.com/Content/ViewContent.aspx?et=$idEducationType&m=$idEducationTypeSelected&ct=$Id"            
                Write-Output "Downloading Page: $uriForTrainingVideo"

                $trainingVideoPageHtml=invoke-webrequest -uri $uriForTrainingVideo
        
                [string]$trainingVideoTitle = $trainingVideoPageHtml.AllElements | Where-Object { $_.tagName.ToLower().StartsWith("title") } | Select-Object -ExpandProperty innerText {$_} 
                $trainingVideoTitle = $trainingVideoTitle.Trim()
                [string]$videoMp4Link = $trainingVideoPageHtml.Links | Where-Object {$_.href.EndsWith(".mp4") -and $_.outerText -eq "MP4"} | Select-Object -ExpandProperty href {$_} 
                $urlFileName = $($videoMp4Link.split("/")[-1])
                $videoMp4LocalFullName = "$($trainingDestination +"\" + $(Remove-InvalidFileNameChars $trainingVideoTitle.Replace(" ","-"))).mp4"

                if(!(Test-Path ($videoMp4LocalFullName))) 
                {
                    Write-Output "Downloading Video: $trainingVideoTitle to $videoMp4LocalFullName"
                    Start-BitsTransfer "$videoMp4Link" $videoMp4LocalFullName
                }
            }
        }
    }
}

Write-Output "Done"